The present invention relates to an interference checking device that checks for interference between the finger, die, and product during press operation in a press that has a transfer device in which the stroke and the like of each shaft (advance-return shaft, clamp-unclamp shaft, lift-down shaft) can be user-specified using a servo motor or a linear motor as a drive source.
By the movement of a pair of feed bars, a transfer press of the prior art conducts press working by holding and transporting material to sequential working stages. The manufacturers of such transfer presses provide an interference chart for the user. The interference chart shows the relationships between the position of the upper mold (slide) and the position of the finger (feed bar) during one rotation of the crank angle. In other words, the interference chart is drawn based on the slide stroke of the press and the strokes of each shaft (advance-return shaft, clamp-unclamp shaft, lift-down shaft) of the transfer device.
Referring to FIG. 5(A), an interference chart of the advance-return shaft is shown. Referring to FIG. 5(B), an interference chart for the clamp unclamp shaft (and in the case of three-dimensions, the lift-down shaft is added) is shown. Referring to FIG. 5(A), the horizontal axis is the stroke of the advance-return shaft (transfer feed stroke), and the vertical axis is the slide stroke of the press. The numerical values (0, 90, 180, 270) on the inside of the chart represent the crank angles. There are two interference charts (F-CUV1, F-CUV2) due to different strokes for the advance-return shaft (transfer feed stroke).
Referring to FIG. 5(B), the horizontal axis is the stroke of the clamp-unclamp shaft (clamp stroke), and the vertical axis is the slide stroke of the press. In a three-dimensional transport in which lift-down motion is conducted, the interference chart of the clamp-lift shaft has the added change in position of the finger (feed bar) during the lift-down motion (C-CUV1). In the case of two-dimensional transport, only the clamp-unclamp direction (C-CUV2) is shown.
Prior to acquiring a transfer press, the user requests from the manufacturer the desired press slide stroke and strokes for each shaft of the transfer device that correspond to the shape of the product to be press worked. In accordance with the desires of the user, the manufacturer provides the interference charts shown in FIGS. 5(A), 5(B). Based on the interference charts provided by the manufacturer, the user decides on the die layout and finger shape and manufactures these. However, due to design mistakes and the like, there is the risk of interference among the fingers, die and product. Therefore, after acquiring the transfer press, there the user must conduct its own interference check by operating the press slide very slowly with the die and fingers attached.
Transfer devices come in two types. A mechanical type uses the rotation of the crank shaft of the press as the drive source. An electrical type uses a servo motor or a linear motor as the drive source. In recent years, due to the rapid advance in electronic devices, the latter transfer device has become standard. In transfer devices of the mechanical type, changing the stroke of each shaft requires the cumbersome process of exchanging mechanical parts such as the cam and the like. In contrast, transfer devices that use servo motors or linear motors as the drive source permit the user to specify the length of the stroke of each shaft within a set range. Therefore, the stroke of each shaft can be changed easily, and a single transfer press can use several dies.
If, after the acquisition of a transfer press, the user decides on a certain stroke for each shaft of the transfer device, the creation of an interference chart, which requires a specialized technique, must be again requested from the manufacturer. This is very complicated. Furthermore, because the actual interference check for the die and the like is conducted after the manufacture of the die and the like, if there is interference, parts such as the die and the like must be reworked to correct the problem. This is extremely time-consuming. In other words, although the settings (stroke and the like for each shaft) for the transfer device are easily changed, the accompanying check for interference among the die, fingers, and product must be determined based on drawings. As a result, the procedure for determining the optimal transfer device settings that match the product (die, fingers) is complicated.